Java Platform, Standard Edition Tools Reference
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3 JDK and JRE File Structure

As of JDK 8u451, JavaFX is no longer included as part of Java SE 8. As a consequence,jfxrt.jar, which contain the JavaFX runtime classes; thejavapackager tool; JavaFX support libraries; and JavaFX entries contained injre/lib/ext/meta-index have been removed. Please visithttps://www.oracle.com/javase/javafx for more information.

This chapter introduces the JDK directories and the files they contain. The file structure of the JRE is identical to the structure of thejre directory in the JDK.

This chapter covers the following topics:

Demos and Samples

Demos and samples that show you how to program for the Java platform are available as a separate download atJava Downloads.

Development Files and Directories

This section describes the most important files and directories required to develop applications for the Java platform. Some of the directories that are not required include Java source code and C header files. SeeAdditional Files and Directories.

jdk1.8.0     bin          java*          javac*          javap*          javah*          javadoc*     lib          tools.jar          dt.jar     jre          bin               java*          lib               applet               ext                    jfxrt.jar                    localdata.jar               fonts               security               rt.jar               charsets.jar

Assuming the JDK software is installed at/jdk1.8.0, here are some of the most important directories:

/jdk1.8.0: Root directory of the JDK software installation. Contains copyright, license, and README files. Also containssrc.zip, the archive of source code for the Java platform.
/jdk1.8.0/bin: Executables for all the development tools contained in the JDK. ThePATH environment variable should contain an entry for this directory.
/jdk1.8.0/lib: Files used by the development tools. Includestools.jar, which contains non-core classes for support of the tools and utilities in the JDK. Also includesdt.jar, theDesignTime archive ofBeanInfo files that tell interactive development environments (IDEs) how to display the Java components and how to let the developer customize them for an application.
/jdk1.8.0/jre: Root directory of the Java Runtime Environment (JRE) used by the JDK development tools. The runtime environment is an implementation of the Java platform. This is the directory referred to by thejava.home system property.
/jdk1.8.0/jre/bin: Executable files for tools and libraries used by the Java platform. The executable files are identical to files in/jdk1.8.0/bin. The java launcher tool serves as an application launcher. This directory does not need to be in thePATH environment variable.
/jdk1.8.0/jre/lib: Code libraries, property settings, and resource files used by the JRE. For examplert.jar contains the bootstrap classes, which are the run time classes that comprise the Java platform core API, andcharsets.jar contains the character-conversion classes. Aside from theext subdirectory, there are several additional resource subdirectories not described here.
/jdk1.8.0/jre/lib/ext: Default installation directory for extensions to the Java platform. This is where theJavaHelp JAR file goes when it is installed, for example. This directory includes thejfxrt.jar file, which contains the JavaFX runtime libraries and thelocaledata.jar file, which contains the locale data for thejava.text andjava.util packages. SeeThe Extension Mechanism.
/jdk1.8.0/jre/lib/security: Contains files used for security management. These include the security policyjava.policy and security propertiesjava.security files.
/jdk1.8.0/jre/lib/sparc: Contains the.so (shared object) files used by the Oracle Solaris release of the Java platform.
/jdk1.8.0/jre/lib/sparc/client: Contains the.so file used by the Java HotSpot VM client, which is implemented with Java HotSpot VM technology. This is the default Java Virtual Machine (JVM).
/jdk1.8.0/jre/lib/sparc/server: Contains the.so file used by the Java HotSpot VM server.
/jdk1.8.0/jre/lib/applet: JAR files that contain support classes for applets can be placed in thelib/applet/ directory. This reduces startup time for large applets by allowing applet classes to be preloaded from the local file system by the applet class loader and provides the same protections as though they had been downloaded over the Internet.
/jdk1.8.0/jre/lib/fonts: Font files used by the platform.

Additional Files and Directories

This section describes the directory structure for Java source code, C header files, and other additional directories and files.

jdk1.8.0     include     man     src.zip

/jdk1.8.0/src.zip

Archive that contains the source code for the Java platform.

/jdk1.8.0/include

C-language header files that support native-code programming with various libraries including:

/jdk1.8.0/man

Contains man pages for the JDK tools.

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3 JDK and JRE File Structure

Demos and Samples

Development Files and Directories

Additional Files and Directories